A base station and use equipment (UE) in a mobile communication system transmits/receives a signal by using a frequency division duplex (FDD) method or a time division duplex (TDD) method. The FDD method separates the signal into different frequency bands, i.e., a transmit frequency and a receive frequency, and the TDD method uses the transmit frequency and the receive frequency together.
FIG. 1 shows connections between a signal monitoring apparatus and a transmitting unit of a TDD-based base station according to a prior art.
As shown in FIG. 1, a transmitting apparatus 100 of the TDD-based base station includes a modem 110, a digital intermediate frequency (IF) unit 120, a radio frequency (RF) unit 130, a high power amplifier (HPA) 140, couplers 160 and 162, and a low noise amplifier (LNA) 150. The transmitting apparatus 100 connects the signal monitoring apparatus and a transmitting unit of the TDD-based base station.
The modem 110 includes a modulator 112 for modulating a data signal into a quadrature phase shift keying (QPSK) signal or a M-ary quadrature amplitude modulation (QAM) signal, and a demodulator 114 for demodulating a digital IF signal into a baseband signal.
The digital IF unit 120 includes an IF up-converter 112 for frequency-up converting a signal modulated by the modulator 112 and a digital to analog (D/A) converter 124 for converting the up-converted digital signal into an analog signal.
The IF signal processed through the D/A converter 124 is converted into an RF signal by an RF up-converter 132, and the RF signal is converted into a high power signal for wireless transmission by the HPA 140, and then the high power signal is passed through an input/output switch and transmitted through an antenna. In this case, an output signal of the HPA 140 is input to the base station monitoring apparatus 180 passed through the coupler 160 and monitored by a signal monitoring apparatus 180.
A signal received through the antenna is input to the LNA 150 and amplified by the LNA 150, and is converted into an RF signal through an RF down-converter 134. The RF signal is input to an A/D converter 126 and converted into a digital IF signal, and the digital IF signal is converted into a baseband signal through a digital IF down-converter 128. The baseband signal is input to the demodulator 114 and demodulated. In this case, an output signal of the LNA 150 is passed through the coupler 162 and input to the signal monitoring apparatus 180 for monitoring the receive signal.
FIG. 2 is a configuration diagram of the signal monitoring apparatus of the base station monitoring apparatus according to the prior art.
As shown in FIG. 2, the signal monitoring apparatus 180 includes a switch 181, an RF down-converter 182, an A/D converter 183, an IF down-converter 184, a signal processor 185, and a control and external interface 186.
The switch 181 selects either a transmit signal or a receive signal for monitoring. An output RF signal of the switch 181 is converted into a predetermined IF frequency (e.g., 70 MHz), and is converted into a baseband signal through the A/D converter 183 and the digital IF down-converter 184. Then, the baseband signal is input to the signal processor 185.
The signal processor 185 measures a baseband signal spectrum and a baseband signal strength, and transmits the measured value to a display medium (e.g., a notebook) through the control and external interface 186.
Such a monitoring apparatus has been typically applied to a base station using a single antenna, and thus, there is no prior art related to application of the monitoring apparatus to a system using multiple antennas.
In addition, when the system using the multiple antennas employs the conventional signal monitoring apparatus, the signal monitoring apparatus of FIG. 2 must be provided for each antenna, and accordingly, a structure of the base station becomes complicated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.